Developers for silver halide films are conventionally prepared from solid ingredients such as hydroquinone, sodium carbonate, sodium bisulfite, potassium bromide, etc. Thus, it is apparent that solid mixtures of appropriate ratios of these ingredients can be converted into working strength developers simply by mixing them in water. In fact, 30 years ago most developers were sold as powders, but long mixing times were required to prepare aqueous solutions for use.
Such powders do not offer the ease of preparation and reproducible results required to meet the needs of small businesses and private practitioners. Today, most developers are sold as liquid concentrates which are easy to mix with water to prepare working strength developers. These concentrates, however, have a relatively short shelf life and the cost of shipment includes the weight of water in the concentrates. Thus, up to the time of the present invention, a real need existed to provide a storage-stable, solid composition which can be readily dissolved to provide a developer which is equivalent in performance to liquid developers and which are more conveniently and economically employed in larger scale operations such as printing shops and hospitals.
Developing agents are known from publications such as Lee and Brown, "The Developing Agents and their Reactions, " The Theory of the Photographic Process, ed. T. H. James, 4th ed., Macmillan, N.Y. (1977), Chapter 11.
Yet, in spite of all that was known about developers in the art, there was no suggestion of how existing techniques could be utilized as described herein to prepare a rapidly dissolving, powdered photographic developer.